JP6034511B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell comprising an impurity removing unit that removes impurities in a raw material and a purification unit that removes harmful components (for example, carbon monoxide and hydrocarbon components) in combustion exhaust gas discharged from the fuel cell. It is about the system.

  Since the fuel cell system is small but has high power generation efficiency, it is being used as a power generation unit in a distributed power generation system. In order for the fuel cell system to function as the power generation unit, it is necessary to stably supply raw materials necessary for power generation to the fuel cell system. Generally, the raw material supplied to the fuel cell system includes natural gas (city gas), LPG, gasoline, kerosene and the like supplied from an existing infrastructure.

  By the way, such a raw material contains, for example, a sulfur compound or a sulfur compound derived from the raw material as an odorant for detecting gas leakage. This sulfur compound poisons the reforming catalyst of the reformer that reforms the raw material to generate the fuel and the electrode catalyst of the fuel cell, and degrades their performance. Therefore, in the fuel cell system, a desulfurization section having a desulfurization catalyst is provided in order to remove sulfur components in the raw material.

  Incidentally, some desulfurization catalysts in the desulfurization part have temperature dependence, and one example thereof is a hydrodesulfurization catalyst used for hydrodesulfurization (hydrodesulfurization) treatment. Therefore, in order to improve the desulfurization performance of the desulfurization section having this hydrodesulfurization catalyst, a fuel cell system (solid oxide) that uses exhaust heat such as radiant heat and heat transfer discharged from the fuel cell or reformer to heat the desulfurization section A fuel cell system) has been proposed. (For example, refer to Patent Document 1).

  Furthermore, a configuration is used in which unused fuel is combusted in the fuel cell, the combustion heat is recovered, and used for reforming reaction in the reformer, preheating of the air supplied to the fuel cell, heating of the desulfurization section, etc. An adopted fuel cell system (solid oxide fuel cell system) has also been proposed. In the case of a fuel cell system having a configuration in which the combustion heat of unused fuel is used for heating in this way, the combustion exhaust gas generated by burning this unused fuel contains harmful substances such as carbon monoxide. Ingredients are included. Therefore, a fuel cell system (solid oxide fuel cell system) provided with a combustion catalyst for oxidizing and decomposing harmful components in the combustion exhaust gas before exhausting the combustion exhaust gas to the outside air has been proposed (for example, a patent). Reference 2).

  In the fuel cell system disclosed in Patent Document 2, a desulfurization section is arranged and heated in the vicinity of a fuel cell that operates at a high temperature, and harmful components such as carbon monoxide contained in combustion exhaust gas generated in the fuel cell. In order to reduce this, a combustion catalyst part is provided at the outlet for discharging the combustion exhaust gas.

JP 2010-272333 A JP 2011-216308 A JP 2008-169100 A

  By the way, in the fuel cell system, it is desired to improve the overall efficiency including power generation efficiency and heat utilization. In order to improve the overall efficiency of the fuel cell system, the amount of heat exhausted from the fuel cell system should be reduced while removing harmful components from the combustion exhaust gas and removing impurities such as sulfur components from the raw material. is important.

  However, in the prior art shown in Patent Documents 1 and 2 described above, removal of harmful components from the combustion exhaust gas and removal of impurities from the raw material are realized while effectively utilizing the heat of the exhaust gas flowing through the fuel cell system. There is a problem that the configuration is not possible.

  The present invention has been made in view of the above-described problems, and the object thereof is to remove harmful components from combustion exhaust gas and from raw materials while effectively utilizing the heat of combustion exhaust gas flowing through the fuel cell system. It is an object of the present invention to provide a fuel cell system that can appropriately remove impurities.

  In order to solve the above-described problems, a fuel cell system according to the present invention includes a fuel cell unit that generates power using a fuel obtained by reforming a supplied raw material and supplied air, and the fuel. An air heat exchange unit that preheats air supplied to the fuel cell unit by heat of combustion exhaust gas generated by burning unused fuel and air in the battery unit, and a part of the heat retained by the preheating of the air An impurity removing unit that removes impurities in the raw material that is heated to a predetermined temperature range by the heat of the lost combustion exhaust gas, a purification unit that removes harmful components contained in the combustion exhaust gas, the impurity removing unit, and A heat exchanging unit that exchanges heat between the heat of the flue gas that has lost some of the heat retained by heating the purification unit and the refrigerant.

  The fuel cell system according to the present invention is configured as described above, and removes harmful components from the combustion exhaust gas and impurities from the raw material while effectively utilizing the heat of the combustion exhaust gas flowing through the fuel cell system. The effect that it can remove appropriately is produced.

1 is a block diagram schematically showing an example of a schematic configuration of a fuel cell system according to Embodiment 1 of the present invention. It is a block diagram which shows schematic structure of the fuel cell unit with which the fuel cell system shown in FIG. 1 is provided. It is a block diagram which shows typically another example of schematic structure of the fuel cell system shown in FIG. 1 is a block diagram schematically showing an example of a schematic configuration of a fuel cell system according to Embodiment 1 of the present invention. It is a block diagram which shows the modification of the fuel cell system which concerns on Embodiment 1 of this invention. It is a block diagram which shows the modification of the fuel cell system which concerns on Embodiment 1 of this invention. It is a block diagram which shows typically an example of schematic structure of the fuel cell system in Embodiment 2 of this invention. It is a flowchart which shows an example of the desulfurization part temperature control process performed in the fuel cell system which concerns on Embodiment 2 shown in FIG. It is a block diagram which shows typically an example of schematic structure of the fuel cell system which concerns on the modification 1 of Embodiment 2 of this invention. 10 is a flowchart showing an example of a combustion catalyst temperature control process executed in the fuel cell system according to Modification 1 of Embodiment 2 shown in FIG. 9. It is a block diagram which shows the modification of the fuel cell system which concerns on Embodiment 2 of this invention. It is a block diagram which shows typically an example of schematic structure of the fuel cell system which concerns on Embodiment 3 of this invention. 13 is a flowchart showing an example of a fuel cell temperature control process in the fuel cell system according to Embodiment 3 shown in FIG. It is a block diagram which shows the modification of the fuel cell system which concerns on Embodiment 3 of this invention. It is a block diagram which shows the modification of the fuel cell system which concerns on Embodiment 3 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  A fuel cell system according to a first aspect of the present invention includes a fuel cell unit that generates electric power using fuel obtained by reforming a supplied raw material and supplied air, An air heat exchanger that preheats the air supplied to the fuel cell unit by the heat of the combustion exhaust gas generated by burning the fuel and air used, and the combustion exhaust gas that has lost part of the heat retained by the air preheating An impurity removing unit that removes impurities in the raw material, a purification unit that removes harmful components contained in the combustion exhaust gas, and an impurity removing unit and a purification unit that are heated to a predetermined temperature range by the heat of A heat exchange unit that exchanges heat between the heat of the flue gas that has lost some of the heat retained by heating and the refrigerant.

  According to the said structure, the heat which combustion exhaust gas has is utilized for the heat source of the heating in an air heat exchange part, an impurity removal part, a purification | cleaning part, and a heat exchange part. For this reason, the heat which the combustion exhaust gas which distribute | circulates a fuel cell system has can be used effectively. Further, impurities are removed from the raw material by the impurity removing unit heated by the heat of the combustion exhaust gas, and harmful components such as carbon monoxide are removed from the combustion exhaust gas by the purification unit heated by the heat of the combustion exhaust gas. be able to. Further, the flue gas that has been heat-utilized in the air heat exchanger and lowered to a predetermined temperature range can be led to the impurity removing unit and the purifying unit. For this reason, the impurity removal unit can appropriately remove impurities, and the purification unit can appropriately remove harmful components such as carbon monoxide.

  Therefore, the fuel cell system according to the first aspect of the present invention removes harmful components such as carbon monoxide from the combustion exhaust gas and effectively uses the heat of the combustion exhaust gas flowing through the fuel cell system. There is an effect that the impurities can be appropriately removed.

  The fuel cell system according to a second aspect of the present invention is the fuel cell system according to the first aspect described above, wherein the heat exchange unit is a water heat exchange unit using water as the refrigerant, and the water heat exchange. The unit may be configured to exchange heat between the heat of the combustion exhaust gas and water to heat the water.

  According to the said structure, since a heat exchange part is a water heat exchange part, heat is exchanged with combustion exhaust gas using water as a refrigerant | coolant, and the heat which combustion exhaust gas holds can be collect | recovered with water. In addition, the combustion exhaust gas is cooled to an appropriate temperature by heat exchange with the water and discharged, and condensed water can be obtained by condensing moisture contained in the exhaust gas as the temperature decreases. For this reason, when there exists a process which requires water in a system, the condensed water obtained from this combustion exhaust gas can be utilized for this process. In addition, as a process which requires water in the system, for example, when a reformer included in a fuel cell reforms a raw material by a steam reforming reaction, a steam reforming reaction process performed in the reformer can be exemplified. .

  The fuel cell system according to a third aspect of the present invention is the fuel cell system according to the first aspect described above, wherein the impurity removal unit is a desulfurization unit that removes sulfur compounds as impurities in the raw material. Good.

  The fuel cell system according to a fourth aspect of the present invention is the fuel cell system according to the third aspect described above, wherein a control unit, a combustion exhaust gas temperature adjustment unit for adjusting the temperature of the combustion exhaust gas, and the desulfurization unit are provided. A desulfurization unit temperature detection unit for detecting a temperature, and the control unit controls the desulfurization unit such that the detected temperature detected by the desulfurization unit temperature detection unit is an upper limit temperature in the predetermined temperature range of the desulfurization unit When it determines with becoming higher than temperature, you may comprise the said flue gas temperature adjustment part so that this detection temperature may become below this desulfurization part control temperature.

  According to the above configuration, since the desulfurization part temperature detection unit is provided, the control unit can grasp the temperature of the desulfurization part. Moreover, the combustion exhaust gas temperature adjustment part is provided. For this reason, when the control unit determines that the detected temperature detected by the desulfurization unit temperature detection unit exceeds the desulfurization unit control temperature, the combustion exhaust gas temperature adjustment unit can be operated to reduce the temperature of the combustion exhaust gas. Therefore, the temperature of the desulfurization part heated using the heat which combustion exhaust gas has can be reduced.

  Therefore, in the fuel cell system according to the fourth aspect of the present invention, the temperature of the desulfurization unit can be adjusted so as not to exceed the desulfurization unit control temperature, and the desulfurization unit is stably heated within a predetermined temperature range. Can do.

  A fuel cell system according to a fifth aspect of the present invention is the fuel cell system according to the third aspect described above, wherein a control unit, a combustion exhaust gas temperature adjustment unit that adjusts the temperature of the combustion exhaust gas, and a purification unit are provided. A purification catalyst temperature detection unit for detecting a temperature, and the control unit is a purification catalyst control in which the detected temperature detected by the purification catalyst temperature detection unit is an upper limit temperature in the predetermined temperature range of the purification unit When it is determined that the temperature is higher than the temperature, the combustion exhaust gas temperature adjustment unit may be operated so that the detected temperature is equal to or lower than the purification catalyst control temperature.

  According to the configuration described above, since the purification catalyst temperature detection unit is provided, the control unit can grasp the temperature of the purification unit. Moreover, the combustion exhaust gas temperature adjustment part is provided. For this reason, when the control unit determines that the detected temperature detected by the purification catalyst temperature detection unit exceeds the purification catalyst control temperature, the combustion exhaust gas temperature adjustment unit can be operated to reduce the temperature of the combustion exhaust gas. . Therefore, the temperature of the purification unit heated using the heat of the combustion exhaust gas can be lowered.

  Therefore, in the fuel cell system according to the fifth aspect of the present invention, the temperature of the purification unit can be adjusted so as not to exceed the purification catalyst control temperature, and the purification unit can be stably heated within a predetermined temperature range. Can do.

  A fuel cell system according to a sixth aspect of the present invention is the fuel cell system according to the third aspect described above, wherein the temperature of the combustion exhaust gas is controlled by controlling the operating temperature of the control unit and the fuel cell unit. A combustion exhaust gas temperature adjusting unit for adjusting; and a fuel cell temperature detecting unit for detecting a temperature in the fuel cell unit, wherein the detected temperature detected by the fuel cell temperature detecting unit is the desulfurization temperature. Or the purifying unit is determined to be higher than the fuel cell control temperature, which is the upper limit temperature in the fuel cell unit, associated with the upper limit temperature in the predetermined temperature range, the detected temperature is the fuel cell control temperature You may be comprised so that the said flue gas temperature adjustment part may be operated so that it may become the following.

  According to the above configuration, since the fuel cell temperature detection unit is provided, the control unit can grasp the temperature in the fuel cell unit. Moreover, the combustion exhaust gas temperature adjustment part is provided. For this reason, when the control unit determines that the detected temperature detected by the fuel cell temperature detecting unit exceeds the fuel cell control temperature, the combustion exhaust gas temperature adjusting unit can be operated to reduce the temperature of the combustion exhaust gas. Therefore, the temperature of the desulfurization section and the purification section heated using the heat of the combustion exhaust gas can be reduced.

  Therefore, the fuel cell system according to the sixth aspect of the present invention adjusts so that the temperature of the desulfurization unit does not exceed the desulfurization unit control temperature, and further, the temperature of the purification unit does not exceed the purification catalyst control temperature. be able to. For this reason, in the fuel cell system according to the sixth aspect of the present invention, the desulfurization section and the purification section can be stably heated within a predetermined temperature range.

  A fuel cell system according to a seventh aspect of the present invention is the fuel cell system according to any one of the third to sixth aspects described above, in which combustion exhaust gas discharged from the fuel cell unit circulates. An exhaust gas path is provided, the desulfurization part has a desulfurization part heating part for heating the desulfurization catalyst filled in the desulfurization part, and the desulfurization part heating part and the purification part are provided in the combustion exhaust gas path It may be configured.

  According to the above configuration, since the desulfurization part heating unit and the purification unit are provided in the combustion exhaust gas path, the heat of the combustion exhaust gas guided by this combustion exhaust gas path is used to remove the desulfurization catalyst and the purification unit of the desulfurization part. The purification catalyst can be heated to a predetermined temperature range.

  A fuel cell system according to an eighth aspect of the present invention is the fuel cell system according to any one of the third to seventh aspects, further comprising a heat insulating member that covers both the desulfurization part and the purification part. In the space formed by the heat insulating member, the desulfurization part and the purification part share a part of the structure forming the desulfurization part and the part of the structure forming the purification part. It may be configured.

  In this way, by configuring the desulfurization unit and the purification unit, both can be efficiently heated by the heat of the combustion exhaust gas in the space formed by the heat insulating member, rather than being configured separately. Can do.

  The fuel cell system according to a ninth aspect of the present invention is the fuel cell system according to the fifth aspect described above, further comprising a purification catalyst heater for heating the purification unit, wherein the control unit includes the purification unit. When it is determined that the detected temperature detected by the catalyst temperature detection unit is lower than the lower limit temperature in the predetermined temperature range of the purification unit, the purification catalyst heater is operated so that the detected temperature becomes equal to or higher than the lower limit temperature. You may be comprised so that it may make.

  According to the above configuration, since the purification catalyst heater is provided, if it is determined that the detected temperature detected by the purification catalyst temperature detection unit is lower than the lower limit temperature in the predetermined temperature range of the purification unit, the purification catalyst heater The purification unit can be heated.

  For this reason, for example, even when the fuel cell system is started from room temperature and the purification unit is not sufficiently warmed, the purification unit can be heated using the purification catalyst heater. Therefore, in the fuel cell system according to the ninth aspect of the present invention, a trace amount of harmful components such as carbon monoxide in the combustion gas is obtained by the purification unit heated to be in a predetermined temperature range from the time of startup. Can be efficiently removed.

  A fuel cell system according to a tenth aspect of the present invention is the above-described fuel cell system according to any one of the third to ninth aspects, wherein the flue gas after heat is used in the desulfurization unit and the purification unit An auxiliary air heat exchanging unit that preheats the air before being supplied to the air heat exchanging unit using the heat of the air heat exchanging unit may be provided.

  According to the above configuration, since the auxiliary air heat exchange unit is provided, the heat of the combustion exhaust gas after being heat-utilized in the desulfurization unit and the purification unit is used to be pre-heated in the air heat exchange unit. Air can be preheated. In this way, the air sent to the air heat exchanger is preheated by the auxiliary air heat exchanger in advance, so that the temperature of the air sent to the fuel cell unit is appropriately increased to the same temperature as the operating temperature of the fuel cell unit. Can do.

  Therefore, the fuel cell system according to the tenth aspect of the present invention can improve the heat availability of the combustion exhaust gas and improve the power generation efficiency.

(Embodiment 1)
[Configuration of fuel cell system]
The configuration of the fuel cell system 100 according to Embodiment 1 will be described with reference to FIGS. FIG. 1 is a block diagram schematically showing an example of a schematic configuration of a fuel cell system 100 according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the fuel cell unit 1 included in the fuel cell system 100 shown in FIG. FIG. 3 is a block diagram schematically showing another example of the schematic configuration of the fuel cell system 100 shown in FIG. 1.

  As shown in FIG. 1, the fuel cell system 100 includes a fuel cell unit 1 serving as a power generation unit, an air heat exchange unit 6, a heat exchange unit 40, an impurity removal unit 41, and a purification unit 42. It is a configuration.

  The fuel cell unit 1 generates power using the fuel obtained by reforming the raw material from which impurities such as sulfur compounds have been removed, and the supplied air, in the impurity removing unit 41. As shown in FIG. 2, the fuel cell unit 1 uses a reforming unit 31 that reforms the raw material from which impurities are removed in the impurity removing unit 41 to generate fuel (reformed gas), and fuel and air. The fuel cell 32 generates electric power through an electrochemical reaction, and the combustion unit 33 combusts unused fuel in the fuel cell 32. That is, the fuel cell unit 1 is a so-called hot module in which the reforming unit 31, the fuel cell 32, and the combustion unit 33 are incorporated.

  In addition, since each part mentioned above with which this fuel cell unit 1 is provided is a well-known member, detailed description of these each member shall be abbreviate | omitted. In the present embodiment, a solid oxide fuel cell (SOFC) will be described as an example of the fuel cell 32, but the fuel cell 32 is not limited to this.

  As shown in FIG. 1, the fuel cell unit 1 is connected to a cathode gas supply path 2 for supplying air as an oxidant gas from outside the system. Further, a combustion exhaust gas path 4 through which the combustion exhaust gas exhausted from the fuel cell unit 1 is circulated to exhaust outside the system and a raw material supply path 5 for supplying raw materials to the fuel cell unit 1 from outside the system are connected. . Here, as a raw material supplied from outside the system, city gas mainly composed of natural gas can be mentioned. Furthermore, when the reforming unit 31 is configured to reform the raw material by steam reforming, a reforming water supply path (not shown) for supplying water from outside the system may be connected.

  The air heat exchange unit 6 preheats the air supplied to the fuel cell unit 1 by using the heat of the combustion exhaust gas discharged from the fuel cell unit 1. In the fuel cell system 100 according to Embodiment 1, a solid oxide fuel cell that operates at a high temperature is used as the fuel cell 32. Therefore, it is necessary to preheat the air supplied to the fuel cell 32 to a temperature close to the operating temperature of the fuel cell 32. Therefore, the air heat exchange unit 6 exchanges heat between the combustion exhaust gas and the air, preheats this air, and supplies it to the fuel cell unit 1.

  Specifically, a cathode gas supply path 2 and a combustion exhaust gas path 4 are connected to the air heat exchange unit 6, and air supplied to the fuel cell unit 1 through the cathode gas supply path 2 and combustion Heat exchange is performed with the combustion exhaust gas discharged from the fuel cell unit 1 through the exhaust gas path 4. Air preheated by heat exchange with the combustion exhaust gas in the air heat exchange unit 6 is supplied to the fuel cell unit 1. On the other hand, the combustion exhaust gas that has lost part of the heat retained by heat exchange with air is supplied to the impurity removal unit 41.

  The impurity removing unit 41 removes impurities contained in the raw material supplied to the fuel cell unit 1. The impurity removal unit 41 is filled with an impurity removal catalyst 52 for removing impurities. As the impurity removal part 41, as shown in FIG. 3, the desulfurization part 8 which removes a sulfur compound as an impurity in a raw material can be illustrated. Further, the desulfurization section 8 is filled with a desulfurization catalyst 22 for removing sulfur compounds in the raw material as the impurity removal catalyst 52, and the raw material is passed through the desulfurization catalyst 22. For example, a copper-zinc-based desulfurization catalyst 22 can be used, and when the desulfurization catalyst 22 is a barrel-zinc system, the temperature dependency that a desired desulfurization performance is obtained in a predetermined temperature range (for example, 200 to 300 ° C.) Have. Therefore, in the fuel cell system 100 according to Embodiment 1, heat exhausted from the air heat exchange unit 6 to preheat the air and guides the combustion exhaust gas in a predetermined temperature range to the desulfurization unit 8. And the desulfurization catalyst 22 is heated using the heat which this combustion exhaust gas has.

  As a configuration for heating the desulfurization catalyst 22 filled in the desulfurization unit 8, for example, the desulfurization unit 8 may be installed in a space where the combustion exhaust gas flows, and the desulfurization unit 8 may be directly heated by the combustion exhaust gas. Furthermore, as shown in FIG. 4, the desulfurization unit 8 may include a desulfurization unit heating unit 20 below the desulfurization catalyst 22, and the desulfurization unit heating unit 20 may heat the desulfurization catalyst 22. In other words, the flue gas is supplied to the desulfurization unit heating unit 20 through the flue gas passage 4, and the heat of the supplied flue gas is transferred to the desulfurization catalyst 22 and heated. FIG. 4 is a block diagram schematically showing an example of a schematic configuration of the fuel cell system according to Embodiment 1 of the present invention.

  In Embodiment 1, a copper-zinc-based desulfurization catalyst is used as the desulfurization catalyst 22, but other desulfurization catalysts may be used. Moreover, desulfurization in the desulfurization part 8 may be performed by the hydrodesulfurization system which makes the raw material containing a sulfur compound react with hydrogen in presence of the desulfurization catalyst 22, for example. Or you may perform using the desulfurization catalyst which the adsorption | suction performance of physical adsorption improves by heating to a predetermined temperature range (for example, patent documents 3).

  In addition, when the desulfurization part 8 is a structure which removes the sulfur compound in a raw material by hydrodesulfurization, hydrogen is mixed with the raw material which distribute | circulates the raw material supply path 5. FIG. This hydrogen may be supplied from outside the system, or a part of the fuel that is reformed and generated by the reforming unit 31 may be supplied. In the case of the latter configuration, the fuel cell system 100 further includes a recycle path (not shown) for returning a part of the fuel (reformed gas) from the fuel cell unit 1 to the upstream side of the desulfurization unit 8 in the raw material supply path 5. Provided. The purifying unit 42 removes harmful components such as carbon monoxide and hydrocarbons contained in the combustion exhaust gas. As shown in FIG. 1, a part of the heat held in the impurity removing unit 41 is used. The later combustion exhaust gas is supplied through the combustion exhaust gas path 4. The purification unit 42 is configured so that the supplied combustion exhaust gas passes through the purification catalyst 53 filled in the purification unit 42. In the first embodiment, as shown in FIG. 3, the combustion catalyst unit 9 can be exemplified as the purification unit 42. When the purification unit 42 is the combustion catalyst unit 9, the purification catalyst 53 can be the combustion catalyst 23 that continues combustion depending on the state. As the combustion catalyst 23, a catalyst in which a Pt-based noble metal catalyst is supported on a honeycomb carrier can be used. However, the combustion catalyst 23 is not limited to this.

  In the fuel cell system 100 according to the first embodiment, as shown in FIG. 3, the combustion exhaust gas is guided to the combustion catalyst unit 9 after passing through the desulfurization unit 8. It is not limited to. For example, the combustion exhaust gas may be guided to the desulfurization unit 8 after passing through the combustion catalyst unit 9 first. These arrangement orders can be determined in consideration of the temperature characteristics of the desulfurization catalyst 22 used in the desulfurization section 8 and the temperature characteristics of the combustion catalyst 23 used in the combustion catalyst section 9.

  As shown in FIG. 1, the heat exchanging unit 40 exchanges heat between the refrigerant supplied from the outside and the combustion exhaust gas discharged to the outside. The heat exchange section 40 is connected to a refrigerant supply path 10 through which a refrigerant supplied from the outside flows, and a combustion exhaust gas path 4 through which the combustion exhaust gas after being used by the combustion catalyst section 9 flows. The heat exchanging unit 40 exchanges heat between the refrigerant supplied through the refrigerant supply path 10 and the combustion exhaust gas supplied through the combustion exhaust gas path 4. Thereby, the temperature of the combustion exhaust gas exhausted outside the system can be lowered to an appropriate temperature. Moreover, the heat exchange part 40 can be made into the water heat exchange part 7 which uses cooling water as a refrigerant | coolant, as shown in FIG. When the heat exchange part 40 is the water heat exchange part 7, the heat | fever which the combustion exhaust gas exhausted out of a system has can be collect | recovered with water. For this reason, the fuel cell system 100 can effectively use the heat of the exhaust gas flowing through the fuel cell system 100. In addition, the heat exchange part 40 is not limited to the above-mentioned water heat exchange part 7, It is good also as a structure which uses a refrigerant | coolant as air and performs heat exchange with this air and combustion exhaust gas. Examples of the heat exchanging unit 40 that performs heat exchange with the combustion exhaust gas using the refrigerant as air include a radiator and the like. However, the water heat exchange unit 7 is more advantageous than the heat exchange unit 40 as a radiator in that the heat of the combustion exhaust gas can be recovered and used with water.

  Furthermore, the heat exchanging unit 40 can be configured to reduce the temperature of the combustion exhaust gas and condense water contained in the combustion exhaust gas to obtain condensed water. The condensed water obtained from the combustion exhaust gas can be used as water used for the steam reforming reaction, for example, when the reforming unit 31 is configured to reform the raw material by the steam reforming reaction.

(Operation of fuel cell system)
Next, the operation of the fuel cell system 100 having the above configuration will be described. In particular, the operation of the fuel cell system 100 is exemplified by a configuration in which the water heat exchange unit 7 is provided as the heat exchange unit 40, the desulfurization unit 8 is provided as the impurity removal unit 41, and the combustion catalyst unit 9 is provided as the purification unit 42. explain.

  As shown in FIGS. 2 and 3, air is supplied to the fuel cell unit 1 through the cathode gas supply path 2 as an oxidant gas supplied to the cathode (not shown) of the fuel cell 32. Further, a raw material for generating fuel supplied to the anode (not shown) of the fuel cell 32 in the reforming unit 31 is supplied to the fuel cell unit 1 through the raw material supply path 5. Further, when steam reforming is performed in the reforming unit 31, the reforming water used in the steam reforming is supplied through a reforming water supply path (not shown).

  In the fuel cell unit 1, power is generated using the air supplied with the fuel cell 32 and the fuel generated in the reforming unit 31 from the supplied raw material. In other words, the reforming unit 31 uses the supplied reforming water and raw materials to cause, for example, a steam reforming reaction to generate a reformed gas containing hydrogen. The reformed gas is supplied to the fuel cell 32 as fuel. Further, the air supplied to the fuel cell 32 together with the fuel is preheated to the operating temperature of the fuel cell 32 in the air heat exchanger 6 as described above.

  In the fuel cell 32, unused fuel and unused air are burned in the combustion section 33, and combustion exhaust gas is generated. This combustion exhaust gas is exhausted from the fuel cell unit 1 through the combustion exhaust gas path 4. An air heat exchange unit 6, a desulfurization unit 8, and a combustion catalyst unit 9 are disposed outside the fuel cell unit 1 in the combustion exhaust gas path 4, and the combustion exhaust gas flows through these parts in order through the combustion exhaust gas path 4. , Lose some of the heat you have in each part. Thereafter, the combustion exhaust gas is further deprived of heat by heat exchange with the cooling water in the water heat exchange section 7. Then, it is exhausted outside the system in a sufficiently low temperature state.

  As described above, the fuel cell system 100 uses the heat of the combustion exhaust gas as a heat source for preheating air. For this reason, compared with the structure which does not use the heat which combustion exhaust gas has, but uses the heating unit etc. which were prepared separately, the utilization factor of the heat utilized within a fuel cell system can be raised.

  In the desulfurization unit 8, the desulfurization catalyst 22 is heated using the heat of the combustion exhaust gas used by the air heat exchange unit 6. That is, for example, when a copper-zinc-based desulfurization catalyst is used as the desulfurization catalyst 22, it is necessary to heat the desulfurization catalyst 22 to around 250 ° C. in order to efficiently remove sulfur compounds in the raw material. By heating the desulfurization section 8 in this way, the temperature of the desulfurization catalyst 22 is raised to a temperature range that is optimal in the catalytic reaction. For example, by hydrodesulfurization using hydrogen contained in the supplied raw material. This raw material is desulfurized. As a result, the raw material that has passed through the desulfurization section 8 is supplied to the fuel cell unit 1 with the sulfur compounding section removed.

  The combustion exhaust gas in which a part of the heat held in the desulfurization unit 8 is used passes through the combustion catalyst unit 9, whereby trace components such as carbon monoxide and hydrocarbons in the combustion exhaust gas are removed. That is, unused fuel and air are combusted in the fuel cell unit 1, and the generated combustion exhaust gas may contain a trace amount of harmful components such as carbon monoxide and hydrocarbons. This is because combustion exhaust gas is generated by flame combustion by the combustion unit 33, and the combustion conditions in this flame combustion are set in consideration of the operating conditions of the fuel cell 32 in which the combustion unit 33 is provided. For this reason, unused fuel and air may not burn completely. Therefore, harmful components such as carbon monoxide and hydrocarbons contained in the combustion exhaust gas are reduced by oxidative decomposition in the combustion catalyst section 9.

  Note that the combustion catalyst 23 filled in the combustion catalyst section 9 has a temperature range (for example, around 250 ° C.) that is optimal for efficient oxidative decomposition. Therefore, the combustion catalyst 23 removes heat from the passing combustion exhaust gas and is raised to this optimum temperature range. The combustion exhaust gas from which harmful components such as carbon monoxide have been removed in the combustion catalyst unit 9 is guided to the water heat exchange unit 7.

  Note that the fuel cell system 100 according to Embodiment 1 has a configuration in which the desulfurization catalyst 22 and the combustion catalyst 23 having close operating temperatures are arranged close to each other. By adopting such a configuration, the desulfurization catalyst 22 and the combustion catalyst 23, which are close in operating temperature, can be combined and heated using the heat of the combustion exhaust gas. It is not necessary to adjust the temperature of the exhaust gas, and heat utilization in the fuel cell system 100 can be improved.

  In addition, since the operating temperatures of the desulfurization catalyst 22 and the combustion catalyst 23 can be stabilized, as a result, the desulfurization performance of the desulfurization catalyst 22 having temperature dependency, and harmful effects such as carbon monoxide in the combustion gas of the combustion catalyst 23 are obtained. The component removal performance can be stabilized.

  In the water heat exchange section 7, harmful components such as carbon monoxide are removed in the combustion catalyst section 9, and between the combustion exhaust gas that has lost some of the heat it holds and the cooling water supplied from outside the system Perform heat exchange. This reduces the temperature of the combustion exhaust gas to a temperature sufficient to exhaust. Thus, since it is the structure which heat-recovers the heat | fever of combustion exhaust gas with cooling water, the temperature of combustion exhaust gas can be reduced effectively and many heat recovery amount can be performed. Thereby, the heat utilization efficiency in the fuel cell system 100 can be further improved.

  In the fuel cell system 100 according to Embodiment 1, the desulfurization unit 8 and the combustion catalyst unit 9 are respectively disposed between the air heat exchange unit 6 and the water heat exchange unit 7 in the combustion exhaust gas path 4. . Both the desulfurization unit 8 and the combustion catalyst unit 9 may be configured as shown in FIG. Here, a configuration in which the desulfurization unit 8 and the combustion catalyst unit 9 are both covered with the heat insulating member 24 will be described as a first modification of the first embodiment with reference to FIG.

(Modification 1 of Embodiment 1)
FIG. 5 is a block diagram showing a modification of the fuel cell system 100 according to Embodiment 1 of the present invention.

  As shown in FIG. 5, in the fuel cell system 100 according to Modification 1 of Embodiment 1, the desulfurization unit 8 and the combustion catalyst unit 9 are accommodated in a space formed by being surrounded by a heat insulating member 24. Thus, since both the desulfurization part 8 and the combustion catalyst part 9 are accommodated in the space formed by the heat insulating member 24, both can be heated with the combustion exhaust gas in the same temperature range, and the combustion exhaust gas It can suppress that the heat which it has dissipates.

  For this reason, since the operating temperature of the desulfurization part 8 and the combustion catalyst part 9 can be stabilized within a predetermined temperature range, the desulfurization performance in the temperature-dependent desulfurization part 8 and the combustion gas in the combustion catalyst part 9 The removal performance of harmful components such as trace amounts of carbon monoxide from can be stabilized. Furthermore, heat utilization in the fuel cell system 100 is improved, and as a result, power generation efficiency is improved.

  Further, as shown in FIG. 5, in the space formed by the heat insulating member 24, a part of the structure forming the desulfurization part 8 and a part of the structure forming the combustion catalyst part 9 are shared with each other. You may comprise. Specifically, in the example of FIG. 5, the contact surfaces of the desulfurization unit 8 and the combustion catalyst unit 9 are shared by both. Thus, by comprising the desulfurization part 8 and the combustion catalyst part 9, both can be efficiently heated with the heat which combustion exhaust gas has rather than setting it as the structure isolate | separated separately.

  Further, in order to efficiently use the heat held in the combustion exhaust gas, the combustion exhaust gas in which a part of the heat held in the desulfurization unit 8 and the combustion catalyst unit 9 is used is guided, and the heat of the combustion exhaust gas is used. It is good also as a structure further provided with the auxiliary air heat exchange part 19 which preheats air. A configuration of the fuel cell system 100 further including the auxiliary air heat exchange unit 19 will be described as a second modification with reference to FIG.

(Modification 2 of Embodiment 1)
FIG. 6 is a block diagram showing a modification of the fuel cell system 100 according to Embodiment 1 of the present invention. As shown in FIG. 6, the fuel cell system 100 according to the second modification of the first embodiment is configured so that the auxiliary air heat exchange unit 19 is connected to the combustion exhaust gas path in the configuration of the fuel cell system 100 according to the first embodiment described above. In FIG. 4, the configuration is provided after the combustion catalyst unit 9 and before the water heat exchange unit 7. A cathode gas supply path 2 is also connected to the auxiliary air heat exchanging section 19, and air before being preheated by the air heat exchanging section 6 is guided through the cathode gas supply path 2.

  The auxiliary air heat exchanging unit 19 exchanges heat between the combustion exhaust gas that has lost a part of the heat held in the combustion catalyst unit 9 and the air, and further takes heat from the combustion exhaust gas. Preheat. Thus, the temperature of the air sent to the fuel cell unit 1 can be increased by preheating the air sent to the air heat exchanger 6 in advance. And the heat availability in the fuel cell system 100 can be improved, and as a result, the power generation efficiency can be improved. Furthermore, when the temperature of the air can be raised to near the operating temperature of the fuel cell unit 1 in the auxiliary air heat exchanging unit 19, the configuration of the air heat exchanging unit 6 can be simplified.

  In the fuel cell system 100 according to Embodiment 1 described above, combustion exhaust gas in a desired temperature range is designed to flow into the desulfurization unit 8 and the combustion catalyst unit 9. By the way, when the operating conditions of the fuel cell unit 1 such as the amount of generated power are changed, the voltage characteristics of the fuel cell 32 change and the amount of heat generated in the fuel cell 32 changes. Alternatively, when the fuel cell 32 deteriorates, the amount of heat generated in the fuel cell 32 changes. For this reason, the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 changes due to the change in the operating conditions of the fuel cell 32 or the deterioration of the fuel cell 32. Furthermore, when the environmental conditions such as the environmental temperature of the fuel cell unit 1 change, the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 also changes.

  As described above, when the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 changes, the operating temperatures of the desulfurization section 8 and the combustion catalyst section 9 may change and deviate from the desired temperature range. For example, when the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 becomes higher than that during rated operation, the desulfurization catalyst 22 and the combustion catalyst 23 are heated at a temperature higher than a desired temperature range. When heated at such a high temperature, the catalyst components of the desulfurization catalyst 22 and the combustion catalyst 23 may be sintered and deteriorated.

  Therefore, the fuel cell system 100 according to Embodiment 1 may be configured to further control the temperature of the combustion exhaust gas flowing into the desulfurization unit 8 and the combustion catalyst unit 9. Hereinafter, a fuel cell system 200 according to Embodiment 2 will be described with reference to FIG. 7 as a fuel cell system further having a configuration capable of controlling the temperature of the flue gas flowing into the desulfurization unit 8 and the combustion catalyst unit 9.

(Embodiment 2)
FIG. 7 is a block diagram schematically showing an example of a schematic configuration of the fuel cell system 200 according to Embodiment 2 of the present invention. As shown in FIG. 7, the fuel cell system 200 according to the second embodiment has a control unit 11, a flue gas temperature cooling unit 12, and a desulfurization unit temperature as compared with the fuel cell system 100 according to the first embodiment. The difference is that the detector 13 is further provided. Since other configurations are the same as those of the fuel cell system 100 of the first embodiment, the description of the same parts is omitted.

  The combustion exhaust gas temperature cooling unit 12 lowers the temperature of the combustion exhaust gas flowing into the desulfurization unit heating unit 20, and corresponds to the combustion exhaust gas temperature adjustment unit of the present invention. Examples of the combustion exhaust gas temperature cooling unit 12 include a cooling device that cools by air cooling using an air fan. However, the combustion exhaust gas temperature cooling unit 12 is not limited to this, and may be another cooling device by air cooling, or a water cooling type cooling device using water as a refrigerant. That is, any configuration that can reduce the temperature of the combustion exhaust gas is optional. The combustion exhaust gas temperature cooling unit 12 is provided at a position on the combustion exhaust gas path 4 that is downstream of the air heat exchange unit 6 and upstream of the desulfurization unit 8 in the flow direction of the combustion exhaust gas.

  The desulfurization unit temperature detection unit 13 detects the temperature of the desulfurization unit 8 and is provided at an arbitrary location in the desulfurization unit 8. The desulfurization unit temperature detection unit 13 notifies the detected temperature of the desulfurization unit 8 to the control unit 11.

  The control unit 11 executes various controls in the fuel cell system 200 and can be realized by, for example, a CPU. When the temperature information detected from the desulfurization unit temperature detection unit 13 is notified, the control unit 11 determines whether or not this temperature exceeds the desulfurization unit control temperature set as the upper limit temperature in the desulfurization unit 8. . And when it determines with having exceeded desulfurization part control temperature, the control part 11 operates the combustion exhaust gas temperature cooling part 12, and controls it so that combustion exhaust gas temperature may be reduced (desulfurization part temperature control process).

  Next, the operation of the fuel cell system 200 according to Embodiment 2 will be described with reference to FIG. The operation of the fuel cell system 200 according to Embodiment 2 is basically the same as that of the fuel cell system 100 according to Embodiment 1, but differs in the following points. That is, the fuel cell system 200 according to Embodiment 2 differs from the fuel cell system 100 according to Embodiment 1 in that the desulfurization part temperature control process shown in FIG. 8 is executed. FIG. 8 is a flowchart showing an example of a desulfurization section temperature control process executed in the fuel cell system 200 according to Embodiment 2 shown in FIG.

  First, a desulfurization section control temperature is set in advance as an upper limit temperature in the desulfurization section 8, and this desulfurization section control temperature is stored in a storage device (not shown). Examples of the storage device include a main memory. When the fuel cell system 200 is operated, the control unit 11 sequentially acquires the temperatures detected by the desulfurization unit temperature detection unit 13 at a predetermined timing (step S11). And the control part 11 compares this acquired temperature with the desulfurization part control temperature memorize | stored in the memory | storage device, and monitors whether the acquired temperature exceeds desulfurization part control temperature (step S12).

  Here, when the control unit 11 determines that the temperature acquired from the desulfurization unit temperature detection unit 13 exceeds the desulfurization unit control temperature (“YES” in step S12), the temperature of the combustion exhaust gas flowing into the desulfurization unit heating unit 20 Is instructed to the flue gas temperature cooling unit 12 so as to be equal to or lower than the desulfurization unit control temperature. In response to the instruction from the control unit 11, the combustion exhaust gas temperature cooling unit 12 decreases the temperature of the combustion exhaust gas so as to be equal to or lower than the desulfurization unit control temperature (step S13).

  As described above, in the fuel cell system 200 according to Embodiment 2, the temperature detected by the desulfurization unit temperature detection unit 13 and the preset desulfurization unit control temperature are compared, and the detected temperature is the desulfurization unit control temperature. In this case, the control unit 11 instructs the combustion exhaust gas temperature cooling unit 12 to control the temperature of the desulfurization unit 8 to be equal to or lower than the desulfurization unit control temperature.

  For this reason, in the fuel cell system 200 according to Embodiment 2, the combustion exhaust gas temperature can be prevented from becoming high and stabilized. Therefore, it is possible to stabilize the operating temperature of the desulfurization unit 8 and further the operating temperature of the combustion catalyst unit 9 provided at the rear stage of the desulfurization unit 8 in the combustion exhaust gas path 4. As a result, the desulfurization performance of the temperature-dependent desulfurization catalyst 22 and the removal performance of harmful components such as trace amounts of carbon monoxide in the combustion gas by the combustion catalyst 23 can be stabilized.

  Note that the preset desulfurization part control temperature can be appropriately set in consideration of the temperature characteristics of the desulfurization catalyst 22 and the temperature characteristics of the combustion catalyst 23, respectively.

  As described above, in the fuel cell system 200 according to Embodiment 2, whether or not to operate the flue gas temperature cooling unit 12 according to whether or not the detected temperature of the desulfurization unit 8 exceeds the desulfurization unit control temperature. The configuration was determined by the control unit 11. However, the present invention is not limited to such a configuration, and the control unit 11 may determine whether or not to operate the combustion exhaust gas temperature cooling unit 12 based on the temperature of the combustion catalyst unit 9. This configuration will be described below as Modification 1 of Embodiment 2 with reference to FIGS.

(Modification 1 of Embodiment 2)
FIG. 9 is a block diagram schematically showing an example of a schematic configuration of a fuel cell system 200 according to Modification 1 of Embodiment 2 of the present invention. FIG. 10 is a flowchart showing an example of the combustion catalyst temperature control process executed in the fuel cell system 200 according to Modification 1 of Embodiment 2 shown in FIG.

  As shown in FIG. 9, the fuel cell system 200 according to the first modification of the second embodiment is different from the fuel cell system 200 according to the second embodiment in that the combustion catalyst temperature is used instead of the desulfurization unit temperature detection unit 13. The difference is that a detector (purified catalyst temperature detector) 14 is provided. Other configurations are the same as those of the fuel cell system 200 of the second embodiment, and thus the description of the same parts is omitted.

  The combustion catalyst temperature detection unit 14 detects the temperature of the combustion catalyst unit 9 and is provided at an arbitrary location in the combustion catalyst unit 9. The combustion catalyst temperature detection unit 14 notifies the detected temperature of the combustion catalyst unit 9 to the control unit 11.

  The operation of the fuel cell system 200 according to the first modification of the second embodiment is almost the same as that of the fuel cell system 200 according to the second embodiment, but differs only in the following points. That is, the fuel cell system 200 according to the first modification of the second embodiment is based on the temperature detected by the combustion catalyst temperature detection unit 14 instead of performing the desulfurization unit temperature control process shown in FIG. It differs in that the combustion catalyst temperature control process shown is carried out.

  Specifically, a combustion catalyst control temperature (purification catalyst control temperature) is set in advance as an upper limit temperature in the combustion catalyst unit 9, and this temperature is stored in a storage device (not shown). When the fuel cell system 200 operates, the control unit 11 sequentially acquires the temperature (detected temperature) detected by the combustion catalyst temperature detection unit 14 at a predetermined timing (step S21). And the control part 11 compares this acquired temperature with the combustion catalyst control temperature memorize | stored in the memory | storage device, and monitors whether the acquired temperature exceeds combustion catalyst control temperature (step S22).

  Here, when the control unit 11 determines that the temperature acquired from the combustion catalyst temperature detection unit 14 exceeds the combustion catalyst control temperature ("YES" in step S22), the temperature of the combustion exhaust gas flowing into the combustion catalyst unit 9 is set. The combustion exhaust gas temperature cooling unit 12 is instructed to lower the temperature to the combustion catalyst control temperature. In response to the instruction from the control unit 11, the combustion exhaust gas temperature cooling unit 12 decreases the temperature of the combustion exhaust gas so as to be equal to or lower than the combustion catalyst control temperature (step S23).

  As described above, in the fuel cell system 200 according to Modification 1 of Embodiment 2, the temperature detected by the combustion catalyst temperature detection unit 14 is compared with a preset combustion catalyst control temperature, and the detected temperature is When the temperature exceeds the combustion catalyst control temperature, the control unit 11 instructs the combustion exhaust gas temperature cooling unit 12 to operate so that the temperature of the combustion catalyst unit 9 becomes equal to or lower than the combustion catalyst control temperature.

  For this reason, in the fuel cell system 200 according to Modification 1 of Embodiment 2, the combustion exhaust gas temperature can be prevented from becoming high and stabilized. Therefore, it is possible to stabilize the temperature of the combustion catalyst unit 9 and also the operating temperature of the desulfurization unit 8 provided immediately before (in front of) the combustion catalyst unit 9 in the combustion exhaust gas path 4. As a result, the desulfurization performance of the temperature-dependent desulfurization catalyst 22 and the removal performance of harmful components such as trace amounts of carbon monoxide in the combustion gas by the combustion catalyst 23 can be stabilized.

  The preset combustion catalyst control temperature can be set as appropriate in consideration of the temperature characteristics of the combustion catalyst 23 and the temperature characteristics of the desulfurization catalyst 22.

  By the way, at the start of operation of the fuel cell system 200 according to Embodiment 2 described above, the operating temperature of the fuel cell unit 1 is lower than the operating temperature at the time of rating, and therefore the temperature of the combustion exhaust gas discharged from the fuel cell unit 1. Also lower. For this reason, the desulfurization catalyst 22 and the combustion catalyst 23 are not heated to a desired temperature range, and the sulfur component cannot be sufficiently removed from the raw material, and harmful components such as carbon monoxide can be sufficiently removed from the combustion exhaust gas. Can not. In particular, exhausting out of the system while containing harmful components such as carbon monoxide in the combustion exhaust gas becomes a big problem. Therefore, the combustion catalyst 23 may be further provided with a combustion catalyst heater (purified catalyst heater) 21 so that the temperature of the combustion catalyst 23 falls within a temperature range corresponding to the temperature characteristics. A configuration further including the combustion catalyst heater 21 will be described below as a second modification of the second embodiment with reference to FIG.

(Modification 2 of Embodiment 2)
FIG. 11 is a block diagram showing a modification (Modification 2) of the fuel cell system 200 according to Embodiment 2 of the present invention. As shown in FIG. 11, the fuel cell system 200 according to Modification 2 of Embodiment 2 further includes a combustion catalyst heater 21 in the configuration of the fuel cell system 200 according to Modification 1 of Embodiment 2. It has a configuration.

  The combustion catalyst heater 21 is a heater that heats the combustion catalyst unit 9 and can be realized by, for example, an electric heater. When the combustion catalyst heater 21 is configured to heat the combustion catalyst 23 by raising the temperature of the combustion exhaust gas supplied to the combustion catalyst unit 9, the flow of the combustion exhaust gas to the combustion catalyst unit 9 in the combustion exhaust gas path 4. Provided near the entrance. On the other hand, in the case where the combustion catalyst unit 9 is directly heated, the combustion catalyst heater 21 is provided in contact with the combustion catalyst unit 9.

  The combustion catalyst heater 21 operates as follows. That is, a predetermined temperature range is set as the operating temperature of the combustion catalyst unit 9, and the lower limit temperature (for example, 200 ° C.) is stored in a storage device (not shown). When the fuel cell system 200 operates, the control unit 11 sequentially acquires the temperatures (detected temperatures) detected by the combustion catalyst temperature detection unit 14 at a predetermined timing. And the control part 11 compares this acquired temperature with the minimum temperature memorize | stored in the memory | storage device, and determines whether the acquired temperature is smaller than a minimum temperature. Here, when the control unit 11 determines that the detected temperature acquired from the combustion catalyst temperature detection unit 14 is lower than the lower limit temperature, the combustion catalyst unit 9 or the temperature of the combustion exhaust gas flowing into the combustion catalyst unit 9 is burned. The combustion catalyst heater 21 is instructed to heat the catalyst 23 until the temperature reaches the lower limit temperature or higher. In response to the instruction from the control unit 11, the combustion catalyst heater 21 heats the combustion catalyst unit 9 or the combustion exhaust gas flowing into the combustion catalyst unit 9 so that the temperature of the combustion catalyst 23 becomes equal to or higher than the lower limit temperature.

  Thus, since the fuel cell system 200 according to the second modification of the second embodiment includes the combustion catalyst heater 21, the combustion catalyst unit 9 is thereby heated to quickly raise the temperature of the combustion catalyst. It is possible to stably remove harmful components such as a small amount of carbon monoxide in the combustion gas. In particular, when the fuel cell system 200 is started from room temperature, the combustion catalyst unit 9 is not sufficiently warmed. However, even in such a case, since the combustion catalyst portion 9 can be heated using the combustion catalyst heater 21, harmful components such as a small amount of carbon monoxide in the combustion gas are removed from the time of startup. be able to.

  By the way, in the fuel cell system 200 according to Embodiment 2 described above, the combustion exhaust gas temperature cooling unit 12 is operated to adjust the temperature of the combustion exhaust gas flowing into the desulfurization unit 8 and the combustion catalyst unit 9. However, the configuration for adjusting the temperature of the combustion exhaust gas is not limited to this configuration. For example, the operating temperature of the fuel cell unit 1 affects the temperature of the combustion exhaust gas discharged from the fuel cell unit 1. When the fuel cell unit 1 is operated at a high temperature, the combustion exhaust gas temperature increases, and as a result, the temperature of the desulfurization catalyst 22 heated by the desulfurization unit heating unit 20 and the combustion catalyst 23 of the combustion catalyst unit 9 increase.

  Therefore, the combustion exhaust gas temperature adjusting unit of the present invention includes a member for controlling the flow rate of air, raw material, or reformed water supplied to the fuel cell unit 1, and adjusts the temperature of the combustion exhaust gas discharged from the fuel cell unit 1. A configuration to be described will be described below as a third embodiment.

(Embodiment 3)
The configuration of the fuel cell system 300 according to Embodiment 3 will be described with reference to FIG. FIG. 12 is a block diagram schematically showing an example of a schematic configuration of a fuel cell system 300 according to Embodiment 3 of the present invention.

  The fuel cell system 300 according to the third embodiment controls the flow rate of air supplied to the cathode of the fuel cell unit 1 in order to stabilize the temperatures of the desulfurization unit 8 and the combustion catalyst unit 9. The operating temperature is configured to fall within a predetermined temperature range. In other words, the fuel cell unit 1 is cooled by increasing the amount of air supplied to the fuel cell unit 1 so that the operating temperature of the fuel cell unit 1 falls within a predetermined temperature range.

  Specifically, as shown in FIG. 12, the fuel cell system 300 according to the third embodiment is different from the configuration of the fuel cell system 200 according to the second embodiment shown in FIG. 7 in the following points. . That is, instead of the desulfurization unit temperature detection unit 13, a combustion catalyst temperature detection unit 14 for detecting the temperature of the combustion catalyst unit 9 is provided. As a combustion exhaust gas temperature adjustment unit, a cathode air supply unit instead of the combustion exhaust gas temperature cooling unit 12. 16 and the fuel cell temperature detector 15 are further provided. Since the other points are the same as the configuration of the fuel cell system 200 according to Embodiment 2, the description thereof is omitted.

  The fuel cell temperature detection unit 15 detects the temperature in the fuel cell unit 1. When the fuel cell temperature detection unit 15 detects the temperature in the fuel cell unit 1, information on the detected temperature is sent to the control unit 11. The fuel cell temperature detection unit 15 is provided at an arbitrary position in the fuel cell unit 1, and particularly near the exhaust port of the combustion exhaust gas. This is because the combustion exhaust gas temperature when discharged from the fuel cell unit 1 can be detected.

  The cathode air supply unit 16 controls the operating temperature of the fuel cell unit 1. Specifically, the operating temperature of the fuel cell unit 1 is controlled by adjusting the amount of air (cathode air) supplied to the fuel cell unit 1. The cathode air supply unit 16 adjusts the flow rate of the supplied air under the control instruction from the control unit 11. That is, the cathode air supply unit 16 adjusts the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 by controlling the operating temperature of the fuel cell unit 1.

  Next, the operation of the fuel cell system 300 according to Embodiment 3 having the above-described configuration will be described. Compared with the operation of the fuel cell system 100 according to the second embodiment, the operation of the fuel cell system 300 according to the third embodiment is shown in FIG. 13 instead of performing the desulfurization part temperature control process shown in FIG. The difference is that the fuel cell temperature control process is performed. FIG. 13 is a flowchart showing an example of a fuel cell temperature control process in the fuel cell system 300 according to Embodiment 3 shown in FIG. The fuel cell system 300 according to the third embodiment is the same as the fuel cell system 200 according to the second embodiment except that the above-described fuel cell temperature control process is performed. Omitted.

  Specifically, a fuel cell control temperature is set in advance as an upper limit temperature in the fuel cell unit 1, and this temperature is stored in a storage device (not shown). This fuel cell control temperature is the upper limit temperature in the fuel cell unit associated with the upper limit temperature in the combustion catalyst unit 9 or the desulfurization unit 8.

  When the fuel cell system 300 operates, the control unit 11 sequentially acquires the temperatures detected by the fuel cell temperature detection unit 15 at a predetermined timing (step S31). And the control part 11 compares this acquired temperature with the fuel cell control temperature memorize | stored in the memory | storage device, and monitors whether the acquired temperature exceeds fuel cell control temperature (step S32).

  Here, when the control unit 11 determines that the temperature acquired from the fuel cell temperature detection unit 15 is higher than the fuel cell control temperature (“YES” in step S32), the fuel cell unit with respect to the cathode air supply unit 16 is determined. An instruction is given to increase the supply amount of air so that the temperature of 1 is lowered to the fuel cell control temperature. In response to the instruction from the control unit 11, the cathode air supply unit 16 increases the amount of air supplied to the fuel cell unit 1 (step S33).

  As described above, in the fuel cell system 300 according to Embodiment 3, the temperature detected by the fuel cell temperature detection unit 15 is compared with the preset fuel cell control temperature, and the detected temperature is the fuel cell control. When the temperature is exceeded, the cathode air supply unit 16 is configured to increase the amount of air supplied to the fuel cell unit 1 under a control instruction from the control unit 11.

  For this reason, in the fuel cell system 300 according to Embodiment 3, the operating temperature of the fuel cell unit 1 can be prevented from becoming high, and can be stabilized to fall within a predetermined temperature range. For this reason, it is possible to prevent the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 from becoming high and the temperature of the combustion catalyst unit 9 and further the temperature of the desulfurization unit 8 from becoming higher than the desired temperature range. Therefore, the operating temperatures of the desulfurization unit 8 and the combustion catalyst unit 9 can be stabilized. As a result, the desulfurization performance of the temperature-dependent desulfurization catalyst 22 and the removal performance of harmful components such as trace amounts of carbon monoxide in the combustion gas by the combustion catalyst 23 can be stabilized.

  In the above description, when the fuel cell control temperature set as the upper limit temperature in the fuel cell unit 1 is exceeded, the cathode air supply unit 16 increases the air supply amount to lower the temperature in the fuel cell unit 1. there were. In this configuration, the fuel cell system 300 may further operate as follows.

  That is, the lower limit temperature in the fuel cell unit 1 is set and stored in the storage device. Then, the controller 11 acquires the temperature detected by the fuel cell temperature detector 15. When it is determined that the detected temperature is lower than the lower limit temperature, the control unit 11 may be configured to control the cathode air supply unit 16 so as to reduce the air supply amount. That is, the cathode air supply unit 16 can suppress the cooling of the fuel cell unit 1 and increase the temperature of the exhaust gas when the flow rate of the air supplied to the fuel cell unit 1 is reduced.

  As described above, in the fuel cell system 300 according to Embodiment 3, the temperature of the fuel cell unit 1 is controlled by adjusting the amount of air supplied from the cathode air supply unit 16 to the fuel cell unit 1. Can control the temperature of the combustion exhaust gas.

  The control unit 11 acquires the fuel cell control temperature, for example, the temperature of the combustion catalyst 23 detected by the combustion catalyst temperature detection unit 14 and the temperature of the fuel cell unit 1 detected by the fuel cell temperature detection unit 15. To do. The temperature of the combustion catalyst 23 and the temperature of the fuel cell unit 1 are correlated, and can be set as appropriate in consideration of a temperature range in which the operations of the desulfurization unit 8 and the combustion catalyst unit 9 are stabilized. .

  Alternatively, a desulfurization unit temperature detection unit 13 is provided instead of the combustion catalyst temperature detection unit 14, and the temperature of the desulfurization catalyst 22 detected by the desulfurization unit temperature detection unit 13 and the fuel cell unit detected by the fuel cell temperature detection unit 15. The control unit 11 acquires the temperature of 1. Then, the temperature of the desulfurization catalyst 22 and the temperature of the fuel cell unit 1 are correlated, and may be set as appropriate in consideration of a temperature range in which the operations of the desulfurization unit 8 and the combustion catalyst unit 9 are stabilized. .

  In the above description, the configuration of the fuel cell system 300 that includes the cathode air supply unit 16 as the combustion exhaust gas temperature adjustment unit and adjusts the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 has been described. However, the configuration is not limited to this configuration. Absent. The fuel cell system 300 includes a raw material supply unit 17 that controls the supply amount of the raw material to the fuel cell unit 1 instead of the cathode air supply unit 16 as a combustion exhaust gas temperature adjustment unit, and combustion exhausted from the fuel cell unit 1 It is good also as a structure which adjusts the temperature of waste gas. Thus, the structure of the fuel cell system 300 provided with the raw material supply part 17 as a combustion exhaust gas temperature adjustment part is demonstrated below with reference to FIG. 14 as the modification 1 of Embodiment 3. FIG.

(Modification 1 of Embodiment 3)
FIG. 14 is a block diagram showing a modification (Modification 1) of fuel cell system 300 according to Embodiment 3 of the present invention. As shown in FIG. 14, the fuel cell system 300 according to Modification 1 of Embodiment 3 includes a cathode air supply unit provided as a combustion exhaust gas temperature adjustment unit in the configuration of the fuel cell system 300 according to Embodiment 3. Instead of 16, a material supply unit 17 is provided. Since the other configuration is the same as that of the fuel cell system 300 of Embodiment 3, the description of the same part is omitted.

  The raw material supply unit 17 controls the flow rate of the raw material supplied to the fuel cell unit 1 under a control instruction from the control unit 11, and is provided in the raw material supply path 5. Here, when the flow rate of the raw material supplied to the fuel cell unit 1 by the raw material supply unit 17 is decreased, unused fuel (reformed gas) to be burned in the combustion unit 33 of the fuel cell unit 1 is decreased. And the temperature of the combustion exhaust gas produced | generated in the combustion part 33 falls.

  On the contrary, when the flow rate of the raw material supplied to the fuel cell unit 1 by the raw material supply unit 17 is increased, unused fuel (reformed gas) to be burned in the combustion unit 33 of the fuel cell unit 1 increases. The temperature of the combustion exhaust gas rises. Therefore, in the fuel cell system 300 according to the first modification of the third embodiment, the raw material supply unit 17 is configured to control the raw material supply amount so that the temperature of the combustion exhaust gas falls within a predetermined temperature range. Yes.

  Specifically, when the control unit 11 determines in step S32 illustrated in FIG. 13 that the temperature acquired from the fuel cell temperature detection unit 15 exceeds the fuel cell control temperature, the fuel cell unit is supplied to the raw material supply unit 17. An instruction is given to reduce the supply amount of the raw material so that the temperature of 1 is lowered to the fuel cell control temperature. In response to an instruction from the control unit 11, the raw material supply unit 17 reduces the amount of raw material supplied to the fuel cell unit 1.

  Furthermore, when the lower limit temperature in the fuel cell unit 1 is set, the control unit 11 determines whether or not the temperature detected by the fuel cell temperature detection unit 15 is lower than the lower limit temperature. And when it determines with the control part 11 being less than minimum temperature, it is good also as a structure which controls the raw material supply part 17 so that the supply amount of a raw material may be enlarged. That is, the raw material supply unit 17 can increase the exhaust gas temperature when the flow rate of the raw material supplied to the fuel cell unit 1 is increased.

  Further, the fuel cell system 300 is configured to control the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 by controlling the supply amount of reforming water instead of controlling the supply amount of air to the fuel cell unit 1. It can also be. The configuration of the fuel cell system 300 that controls the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 by controlling the amount of reforming water supplied to the fuel cell unit 1 in this manner is a modification of the third embodiment. 2 will be described below with reference to FIG.

(Modification 2 of Embodiment 3)
FIG. 15 is a block diagram showing a modification (Modification 2) of the fuel cell system 300 according to Embodiment 3 of the present invention. As shown in FIG. 15, the fuel cell system 300 according to Modification 2 of Embodiment 3 supplies water instead of the cathode air supply unit 16 provided in the configuration of the fuel cell system 300 according to Embodiment 3. The water supply part 18 and the fuel cell unit 1 are different by the point which is provided with the reforming water path | route (not shown). Since the other configuration is the same as that of the fuel cell system 300 of Embodiment 3, the description of the same part is omitted.

  The water supply unit 18 supplies reformed water for use in steam reforming to the reforming unit 31 in the fuel cell unit 1 through the reformed water path under the instruction from the control unit 11. Note that the reformed water supplied from the water supply unit 18 may be water supplied from an external water source, or combustion that has been cooled by heat exchange between the combustion exhaust gas and the water heat exchange unit 7. It may be condensed water obtained from exhaust gas.

  Here, when the flow rate of the reforming water supplied to the fuel cell unit 1 by the water supply unit 18 is increased, the amount of heat necessary for evaporating the reforming water in the evaporator (not shown) of the fuel cell unit 1 is increased. To increase. For this reason, the amount of heat of the combustion exhaust gas used for the evaporation of the reformed water increases, and as a result, the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 decreases. On the other hand, when the flow rate of the reforming water supplied to the fuel cell unit 1 by the water supply unit 18 is decreased, the amount of heat required for evaporating the reforming water in the evaporator of the fuel cell unit 1 decreases. For this reason, the amount of heat of the combustion exhaust gas used for the evaporation of the reformed water is reduced, and as a result, the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 is increased.

  Therefore, in the fuel cell system 300 according to the second modification of the third embodiment, the temperature of the combustion exhaust gas is changed within a predetermined temperature range by utilizing the point that the temperature of the combustion exhaust gas changes according to the flow rate of the reforming water to be supplied. It is configured to control the amount of reforming water supplied by the water supply unit 18 so as to be contained within.

  Specifically, when the control unit 11 determines in step S32 shown in FIG. 13 that the temperature acquired from the fuel cell temperature detection unit 15 exceeds the fuel cell control temperature, the fuel cell unit is supplied to the water supply unit 18. An instruction is given to increase the supply amount of reforming water so that the temperature of 1 is lowered to the fuel cell control temperature. In response to the instruction from the control unit 11, the water supply unit 18 increases the supply amount of reforming water to the fuel cell unit 1.

  Furthermore, when the lower limit temperature in the fuel cell unit 1 is set, the control unit 11 determines whether or not the temperature detected by the fuel cell temperature detection unit 15 is lower than the lower limit temperature. And when it determines with the control part 11 falling below a minimum temperature, it is good also as a structure which controls so that the supply_amount | feed_rate of reforming water may be made small. That is, the water supply unit 18 can increase the temperature of the exhaust gas when the flow rate of the reforming water supplied to the fuel cell unit 1 is reduced.

  The fuel cell system 300 according to the third embodiment and the modifications 1 and 2 described above can keep the temperature of the combustion exhaust gas discharged from the fuel cell unit 1 within a predetermined temperature range. For this reason, both the temperature of the desulfurization part 8 and the temperature of the combustion catalyst part 9 can be kept within a predetermined temperature range, and the desulfurization performance of the desulfurization catalyst 22 having temperature dependency and the trace amount in the combustion gas of the combustion catalyst 23 are obtained. The ability to remove harmful components such as carbon monoxide can be stabilized.

  The fuel cell system according to the present invention is useful in a fuel cell system including a hydrodesulfurization unit that removes sulfur components in a raw material and a combustion catalyst unit that removes harmful components such as carbon monoxide contained in combustion exhaust gas. is there.

DESCRIPTION OF SYMBOLS 1 Fuel cell unit 2 Cathode gas supply path 4 Combustion exhaust gas path 5 Raw material supply path 6 Air heat exchange part 7 Water heat exchange part 8 Desulfurization part 9 Combustion catalyst part 10 Refrigerant supply path 11 Control part 12 Combustion exhaust gas temperature cooling part 13 Desulfurization part Temperature detector 14 Combustion catalyst temperature detector (purified catalyst temperature detector)
DESCRIPTION OF SYMBOLS 15 Fuel cell temperature detection part 16 Cathode air supply part 17 Raw material supply part 18 Water supply part 19 Auxiliary air heat exchange part 20 Desulfurization part heating part 21 Combustion catalyst heater (purification catalyst heater)
22 Desulfurization catalyst 23 Combustion catalyst 24 Heat insulation member 31 Reforming unit 32 Fuel cell 33 Combustion unit 40 Heat exchange unit 41 Impurity removal unit 42 Purification unit 52 Impurity removal catalyst 53 Purification catalyst 100 Fuel cell system 200 Fuel cell system 300 Fuel cell system

Claims (4)

A reforming unit that reforms the supplied raw material to generate fuel, a fuel cell that generates electric power using the fuel and the supplied air, and combustion exhaust gas by burning the unused fuel in the fuel cell A fuel cell unit having a combustion section for generating
A combustion exhaust gas path for circulating the combustion exhaust gas discharged from the fuel cell unit;
An air heat exchanger that preheats the air supplied to the fuel cell unit by the heat of the combustion exhaust gas generated by the combustion of the combustion unit in the fuel cell unit;
A sulfur compound is removed as an impurity in the raw material that is provided in the combustion exhaust gas path and is heated to a predetermined temperature range by the heat of the combustion exhaust gas that has lost some of the heat retained by the preheating of the air. A desulfurization section that performs and a purification section that removes harmful components contained in the combustion exhaust gas,
A heat exchanging section that exchanges heat between the heat of the flue gas that has lost some of the heat retained by heating the desulfurization section and the purification section, and the refrigerant;
A control unit;
A flue gas temperature adjusting unit for adjusting the temperature of the flue gas,
A desulfurization section temperature detection section for detecting the temperature of the desulfurization section or a purification catalyst temperature detection section for detecting the temperature of the purification section;
A heat insulating member that covers both the desulfurization part and the purification part;
With
In the space formed by the heat insulating member, the desulfurization unit and the purification unit are configured to share a part of the structure forming the desulfurization unit and a part of the structure forming the purification unit. Has been
Outside the space formed by the heat insulating member, the fuel cell unit, the air heat exchange unit, and the heat exchange unit are arranged,
The controller is
When it is determined that the detected temperature detected by the desulfurization unit temperature detection unit is higher than the desulfurization unit control temperature that is the upper limit temperature in the predetermined temperature range of the desulfurization unit, the detected temperature is equal to or lower than the desulfurization unit control temperature. To operate the combustion exhaust gas temperature adjustment unit, or
When it is determined that the detected temperature detected by the purification catalyst temperature detection unit is higher than the purification catalyst control temperature that is the upper limit temperature in the predetermined temperature range of the purification unit, the detected temperature is equal to or lower than the purification catalyst control temperature. A fuel cell system for operating the combustion exhaust gas temperature adjustment unit. The heat exchange part is a water heat exchange part using water as the refrigerant,
2. The fuel cell system according to claim 1, wherein the water heat exchanger exchanges heat between the heat of the combustion exhaust gas and water to heat the water. A purification catalyst heater for heating the purification unit;
When the control unit determines that the detected temperature detected by the purification catalyst temperature detection unit is smaller than the lower limit temperature in the predetermined temperature range of the purification unit, so that the detected temperature is equal to or higher than the lower limit temperature, The fuel cell system according to claim 1, wherein the purification catalyst heater is operated.   The auxiliary air heat exchange part which preheats the air before being supplied to the said air heat exchange part using the heat | fever which the combustion exhaust gas after being heat-utilized by the said desulfurization part and the said purification | cleaning part is provided. The fuel cell system according to any one of?

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